Asthma control in overweight or obese adolescents and young adults do not improve with supplementation of fish oil, reveals a new study. The research is published in the journal Annals of the American Thoracic Society.
In "Fish Oil Supplementation in Overweight/Obese Patients with Uncontrolled Asthma: A Randomized Trial," Jason E. Lang, MD, MPH, and co-authors report that four grams of fish oil a day for six months did not improve asthma control, as measured by a standard asthma control questionnaire, breathing tests, urgent care visits and severe asthma exacerbations.
"We don't know why asthma control in obese patients is more difficult, but there is growing evidence that obesity causes systemic inflammation," said Dr. Lang, lead study author and associate professor of pediatrics at Duke University. "Because the omega-3 fatty acids in fish oil have anti-inflammatory properties, we wanted to test whether fish oil would have therapeutic benefits for these patients."
The researchers also looked at whether a variant in the gene ALOX5 affected study findings. It is known that mutations in the gene can reduce responses to anti-leukotriene drugs. Leukotrienes are inflammatory molecules that play a critical role in triggering asthma attacks. In this study, the ALOX5 variant did appear to be linked to leukotriene production but not to the effectiveness of fish oil in providing asthma control.
The authors wrote that the study's negative findings may not be the last word on fish oil and asthma. They acknowledged that larger doses of fish oil over a longer period of time may produce a different result.
Based on the current study, however, "there is insufficient evidence for clinicians to suggest to patients with uncontrolled asthma that they should take daily fish oil supplements to help their asthma," Dr. Lang said.